Transaction.fromReader constructor

Transaction.fromReader(BytesReader reader, { bool? expectWitness, })

Reads a transaction from a BytesReader, which may throw TransactionTooLarge or InvalidTransaction if the data doesn't represent a complete transaction within maxSize (1MB). If expectWitness is true, the transaction is assumed to be a witness transaction. If it is false, the transction is assumed to be a legacy non-witness transaction. If expectWitness is omitted or null, then this method will determine the correct transaction type from the data, starting with a witness type.

Implementation

factory Transaction.fromReader(BytesReader reader, { bool? expectWitness }) {

  bool tooLarge = false;
  final start = reader.offset;

  Transaction? tryReadAndSetTooLarge(bool witness) {
    try {
      return _tryRead(reader, witness);
    } on TransactionTooLarge {
      tooLarge = true;
    } on Exception catch(_) {}
    return null;
  }

  if (expectWitness != false) { // Includes null condition
    final witnessTx = tryReadAndSetTooLarge(true);
    if (witnessTx != null) return witnessTx;
  }

  // Reset offset of reader
  reader.offset = start;

  if (expectWitness != true) { // Includes null condition
    final legacyTx = tryReadAndSetTooLarge(false);
    if (legacyTx != null) return legacyTx;
  }

  throw tooLarge ? TransactionTooLarge() : InvalidTransaction();

}